Apparatus for testing flat panel display

ABSTRACT

Apparatus for testing flat panel display (liquid crystal display) panel is disclosed herein. Testing apparatus for sending a plurality of electrical signals to a plurality of pads of a display panel, the testing apparatus includes the following devices. A plurality of probe pins is used to contact the plurality of pads of the display panel. The amount of the plurality of probe pins in the present invention is larger than the amount of the plurality of pads, besides, the pitches between the plurality of probe pins is smaller than the width of etch of the plurality of pads of the display panel. The signal generating means is used to generate the signals to be sent to the plurality of pads of the display panel through the plurality of probe pins. The switching means is used to provide the conductive paths between the signal generating means and the plurality of probe pins.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to apparatus for testing flat panel display, andparticularly relates to apparatus for testing liquid crystal display(LCD).

2. Description of the Prior Art

As the trend of shrinking volume of electrical device and reducingradiation produced by the display device, the cathode ray tube (CRT)display is gradually replaced with the flat panel display. But thetechnology for fabricating the flat panel display device results in thehigh cost of the flat panel display device, which confines the use offlat panel display device. After a long term of developing thefabricating technology for manufacturing flat panel display device, suchas LCD, the yield of fabricating LCD is raised, and the technology isgetting mature day by day. In recent years, application of flat paneldisplay devices to word processors, lap-top personal computers, pocketsize TV display, and the like have been rapid progress. Especially, theliquid crystal display (LCD) is widely used in every kinds ofapplication due to the maturity of process that fabricating the LCDpanel.

In early years, because LCD is very expensive, and the technology isimmature, the application of LCD is only in a narrow field, thus onlyfew sizes of LCD is utilized in few applications. As the fabricationtechnology progressed, the yield of fabricating LCD is raised, and costis down gradually. So the application of LCD is getting more wide, andthe size of LCD is getting larger. To replace the CRT display, theenlargement of the area of the LCD panel is necessary, so the technologyused to fabricate the large size LCD panel is developed. Though thelarge size LCD is getting more popular, the application of small sizeLCD is unavoidable.

Because the LCD panel is composed of many LCD cells and other devices,in addition, the larger LCD panel has more devices. Even a single devicein the LCD panel is out of order, the whole LCD panel is thus fail. Sothe test for the fabricated LCD panel is a very important step to ensurethe quality of the fabricated LCD panel before packaging. To verifywhether the fabricated LCD panel can work properly, the probe card isutilized to test the fabricated LCD panel. In earlier years, only fewkinds of LCD sizes are utilized in application, so only few kinds ofsizes of probe card are utilized to test the LCD panel. Though only fewkinds of sizes of probe card are utilized, and each size of probe cardis designed for a specific LCD size, because few sizes of LCD panel areutilized, so that few sizes of probe card are enough.

Due to various applications of LCD panel, the LCD panel of various sizesare developed, and the probe card of corresponding sizes are designedand fabricated to test the LCD panel of corresponding size. Whereas inthe LCD panel factory, one test station can only test LCD panels of onespecific size. If the size of the produced LCD panel is to be changed,the probe card must be replaced to fit the new size of the produced LCDpanel. To illustrate the operation of the prior art probe card utilizedto test the flat panel display, such as LCD panel, the configuration ofthe prior art LCD panel testing device is illustrated in FIG. 1a, inwhich the probe card is utilized. As shown in FIG. 1a, the LCD paneltesting device includes the pattern generator 10, the control board 13,the scan circuit board 15, the data circuit board 17, and the probe card19. Besides the LCD panel that is to be tested is LCD panel 25. Whentesting the LCD panel 25, the pattern generator 10 generates the patternthat is to be shown in the display panel (LCD panel 25). The controlboard 13 feeds a data line driving signal ds to the data circuit board17 and feeds a scan line driving signal ss to the scan circuit board 15respectively according to the output signal of the pattern generator 10.The scan circuit board 15 feeds the scan line driving pulse sp to theprobe card 19 responding to the scan line driving signal ss, and feedsthe data line driving pulse dp to the probe card 19 responding to thedata line driving signal ds.

To further illustrate the operation of testing the LCD panel, theamplified view of the area in the dashed circle D in FIG. 1a is shown inFIG. 1b. In which a plurality of probe pin 27 is electrically coupled tothe edge of probe card respectively, and the other terminal of each ofthe plurality of probe pin 27 is also electrically coupled to the pad 30of the LCD panel 25 by physical touching. So the devices in the LCDpanel can be tested by the LCD panel testing device through the probecard 19. For the description mentioned above, the number of pin 27 ofthe probe card 19 is fixed and the size of the probe card 19 is fixed.If a new LCD panel has a larger size than that of the original LCDpanel, it is impossible to use the original probe card to test the LCDpanel of a larger size. Also, if the size of the fabricated LCD panel ofthe production line is to be changed. In other words, when theproduction line is used to fabricate the LCD panel of the other size,then the probe card on the production line must be changed to a specificsize that fits for the of the other size of LCD panel. It takes about1-2 hours to change the probe card of the production line, and it's along time wasted in fabricating LCD panel.

In addition, in developing a specific LCD panel, it is necessary to testthe fabricated specific LCD panel, so the purchase of the probe card ofcorresponding specification is necessary. Whereas each probe card costsabout 10,000 US dollars, its very expensive, and if the developedspecific LCD panel is not to be mass produced, the probe card ofcorresponding specification will become useless, thus the waste ofinvestment is resulted. Furthermore, as the technology advances gettingmore quickly, LCD of one specification will probably be replaced withLCD of another specification within the lifetime of the ordinary probecard. So the replacement of a new probe card is necessary, and theordinary probe card become useless.

Besides, it takes about two months for the probe card maker from gettingan order for purchasing a probe card to realizing the designed probecard. If the foregoing duration can be saved, it makes benefit indeveloping the LCD of a new specification. In other words, the durationof developing a LCD panel of a new specification is reduced. Accordingto the disadvantages mentioned above, the prior art probe card needsimprovement.

SUMMARY OF THE INVENTION

Apparatus for testing flat panel display (liquid crystal display) panelis disclosed herein. The testing apparatus for sending a plurality ofelectrical signals to a plurality of pads of a display panel, thetesting apparatus includes the following devices. A plurality of probepins is used to contact the plurality of pads of the display panel. Theamount of the plurality of probe pins in the present invention is largerthan the amount of the plurality of pads, besides, the pitches betweenthe plurality of probe pins is smaller than the width of etch of theplurality of pads of the display panel. The signal generating means isused to generate the signals to be sent to the plurality of pads of thedisplay panel through the plurality of probe pins. The switching meansis used to provide the conductive paths between the signal generatingmeans and the plurality of probe pins.

Generally speaking, the tested display panel can be a liquid crystaldisplay panel. In one preferred embodiment of the present invention, theswitching means can includes contact detection means, processing means,and matching means. The contact detection means is used to detect whichof the plurality of probe pins are in contact with the plurality ofpads. The processing means is used to provide a decoded signalrepresenting a mapping relation between the signals to be sent to thedisplay panel and the plurality of probe pins in contact with theplurality of pads according to the result of the contact detectionmeans. The matching means is used to provides conductive paths betweenthe signal generating means and the plurality of pads of the displaypanel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features of the present invention will be more clearlyunderstood from consideration of the following descriptions inconnection with accompanying drawings in which:

FIG. 1a illustrates the configuration of the prior art testing apparatusfor testing the display panel;

FIG. 1b illustrates the amplified view of a portion of the configurationof the prior art testing apparatus;

FIG. 2a illustrates the configuration of the testing apparatus accordingto one preferred embodiment of the present invention;

FIG. 2b illustrates the amplified view of a portion of the configurationof the testing apparatus according to one preferred embodiment of thepresent invention;

FIG. 3 illustrates the configuration of the switching box utilized inone preferred embodiment of the present invention; and

FIG. 4 illustrates one of the practical configurations that canimplement the switch box can be used in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

To improve the prior art probe card for testing whether every device ofa flat panel display can work properly, the present invention proposesapparatus for testing flat panel display. The preferred embodiment ofthe present invention use apparatus for testing LCD panel as an exampleto illustrate how the apparatus according to one preferred embodiment ofthe present invention works.

To illustrate the operation of the apparatus for testing the flat paneldisplay, such as LCD panel, the configuration of the LCD panel testingdevice is illustrated in FIG. 2a, in which the probe card is utilizedaccording to one preferred embodiment of the present invention. As shownin FIG. 2a, the LCD panel testing apparatus includes the patterngenerator 50, the control board 55, the scan circuit board 60, the datacircuit board 65, the switching box for scan 70, the switching box fordata 75, and the probe card 80. In addition, in the preferred embodimentof the present invention shown in FIG. 2A, the LCD panel that is to betested is LCD panel 85. When testing the LCD panel 85, the patterngenerator 50 generates the pattern that is to be shown in the displaypanel (LCD panel 85). The control board 55 feeds a data line drivingsignal ds to the data circuit board 65 and feeds a scan line drivingsignal ss to the scan circuit board 60 respectively according to theoutput signal of the pattern generator 50. The scan circuit board 60feeds the scan line driving pulse sp to the switch box for scan 70responding to the scan line driving signal ss, and feeds the data linedriving pulse dp to the switching box for data 75 responding to the dataline driving signal ds. Then the switch box for scan 70 feeds thepredetermined scan line testing pulse st to the probe card 80 respondingto the scan line driving pulse sp, and the switch box for data 75 feedsthe predetermined data line testing pulse dt to the probe card 80responding to the data line driving pulse dp.

To further illustrate the operation of testing the LCD panel, theamplified view of the area in the dashed circle E in FIG. 2a is shown inFIG. 2b. In which a plurality of probe pin 90 is electrically coupled tothe edge of probe card 80 respectively, and the other terminal of eachof the plurality of probe pin 90 is also electrically coupled to the pad95 of the LCD panel 85 by physical touching. So the devices in the LCDpanel can be tested by the LCD panel testing apparatus through the probecard 80. For the description mentioned above, it is noted that, thoughthe pin number is fixed, yet the number of probe pin 90 of the probecard 85 according to one preferred embodiment of the present inventionis more than the number of pad 95 of the LCD panel 85. In addition, thepitch between the probe pins 80 is smaller than the width of the pad 95,so every pad 95 can be electrically coupled to the probe card 80 by theplurality of probe pins 90. FIG. 2b is the top view of the configurationof a portion of the preferred embodiment of the present invention shownin FIG. 2a within dashed circle E.

To describe how the display panel testing apparatus according to thepreferred embodiment of the present invention, the configuration of theswitching box utilized in the preferred embodiment of the presentinvention is illustrated in FIG. 3. The switching box for scan 70 andthe switching box for data 75 are of the same configuration as shown inFIG. 3. As shown in FIG. 3, the switching box 105 includesmicro-processor 110, pin contact detection circuit 115, and the signalversus pin match circuit 120. The signal from the signal generator (scancircuit board 60 or the data circuit board 65) is fed to the switch box105. The switch box 105 detects which probe pin is connected to the padof the display panel, and determine the mapping between the probe pin incontact with the pad and the signal that is to be sent to the probe pin.The pin contact detection circuit 115 detects which probe pin of theprobe card is in contact with the pad of the LCD panel. The signalversus pin match circuit 120 set up the map between the probe pinsconnected to the pads and the signals that are to be sent to the pads.In other words, the signal versus pin match circuit 120 provides thepath between the signals form the signal generator to the plurality ofprobe pins, which contact with the pads. The micro-processor 110 enablesthe pin contact detection circuit 115 to detect the which pins areconnected to the pads, and the results are sent to the micro-processor110.

Thus the micro-processor 110 assign the conducting path between thesignal generator and the plurality of probe pins. Because the size(number of pin) of the probe card utilized in the preferred embodimentof the present invention is larger than the usual size (number of pads)of the tested display panel. Due to the operation mentioned above, thetest signals from the signal generator can be sent to the correspondingpads through the probe pins, thus the test signals can be transmittedfrom the pins to the devices in the display panel through thecorresponding scan bus and data bus. As long as the number of pin of theprobe card is greater than the number of pad, the display testingapparatus according to the preferred embodiment of the present inventioncan be used to test the electrical characteristic of the devices in thedisplay panel of various sizes.

As the signal versus pin match circuit 120 in the switching box 105 canreceive the decoded signal representing the mapping relation between thesignal generator to be sent to the display panel and the plurality ofprobe pins in contact with the plurality of pads according to the resultof the pin contact detection circuit 120. So the signal versus pin matchcircuit 120 can provide the conductive paths between the signalgenerator and the plurality of probe pins. The signal versus pin matchcircuit 120 in the preferred embodiment of the present invention can bean electrical switch. As to carry out the practical circuit of theswitch box (shown in FIG. 3), it can be implemented in many forms ofconfiguration, and one of the practical configuration is shown in FIG.4.

As will be understood by persons skilled in the art, the foregoingpreferred embodiment of the present invention is illustrative of thepresent invention rather than limiting the present invention. Havingdescribed the invention in connection with a preferred embodiment, forexample, if various kinds of display are tested or variousconfigurations of the switch box are utilized in the preferredembodiment. As long as the probe card used to test the display panel hasa larger size (number of pins) than that of the tested display panel(number of pads), the modification will now suggest itself to thoseskilled in the art. While the preferred embodiment of the invention hasbeen illustrated and described, it will be appreciated that variouschanges can be made therein without departing from the spirit and scopeof the invention.

What is claimed is:
 1. Testing apparatus for testing an electricalcharacteristic of devices of a display panel, said testing apparatuscomprising: signal generating means for generating signals that are tobe sent to a plurality of pads of said display panel; switching meansfor providing a conductive path between said signal generating means andsaid plurality of pads of said display panel, wherein said plurality ofswitching means comprises: contacting detection means detecting which ofsaid plurality of probe pins are in contact with said plurality of pads;processing means for providing a decoded signal representing a mappingrelation between said plurality of electrical signals to be sent to saiddisplay panel and said plurality of probe pins in contact with saidplurality of pads according to the result of said contacting detectionmeans; and matching means for providing conductive path between saidsignal generating means and said plurality of pads of said display panelaccording to said decoded signal; contacting conductive means fordirectly feeding said signals to said plurality of pads, said contactingconductive means contacting said plurality of pads, an amount of saidcontacting conductive means being larger than an amount of saidplurality of probe pins, a pitch between any neighboring two of saidplurality of probe pins being smaller than a width of each of saidplurality of pads of said display panel.
 2. Apparatus as claim 1,wherein said display panel is a liquid crystal display panel.
 3. Testingapparatus for testing an electrical characteristic of a device of adisplay panel, said testing apparatus comprising: a plurality of probepins for contacting a plurality of pads of said display panel, saidtesting apparatus being used for sending a plurality of electricalsignals to said plurality of pads of said display panel to test theelectrical characteristic of the device of said display panel, an amountof said plurality of probe pins being larger than an amount of saidplurality of pads, pitches between said plurality of probe pins beingsmaller than widths between said plurality of pads of said displaypanel; signal generating means for generating signals to be sent to saidplurality of pads of said display panel through said plurality of probepins; and switching means for providing a conductive path between saidsignal generating means and said plurality of probe pins, wherein saidplurality of switching means comprises: contacting detection meansdetecting which of said plurality of probe pins are in contact with saidplurality of pads; processing means for providing a decoded signalrepresenting a mapping relation between said plurality of electricalsignals to be sent to said display panel and said plurality of probepins in contact with said plurality of pads according to the result ofsaid contacting detection means; and matching means for providingconductive path between said signal generating means and said pluralityof pads of said display panel according to said decoded signal. 4.Apparatus as claim 3, wherein said display panel is a liquid crystaldisplay panel.